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             AUSCERT External Security Bulletin Redistribution

                      USN-4967-1: nginx vulnerability
                                27 May 2021


        AusCERT Security Bulletin Summary

Product:           nginx
Publisher:         Ubuntu
Operating System:  Ubuntu
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Denial of Service               -- Remote/Unauthenticated
                   Access Confidential Data        -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-23017  

Reference:         ESB-2021.1802

Original Bulletin: 

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USN-4967-1: nginx vulnerability
26 May 2021

nginx could be made to crash or run programs if it received specially
crafted network traffic.

  o Ubuntu 21.04
  o Ubuntu 20.10
  o Ubuntu 20.04 LTS
  o Ubuntu 18.04 LTS


  o nginx - small, powerful, scalable web/proxy server


Luis Merino, Markus Vervier, and Eric Sesterhenn discovered that nginx
incorrectly handled responses to the DNS resolver. A remote attacker could
use this issue to cause nginx to crash, resulting in a denial of service,
or possibly execute arbitrary code.

Update instructions

The problem can be corrected by updating your system to the following package

Ubuntu 21.04

  o nginx-extras - 1.18.0-6ubuntu8.2
  o nginx-core - 1.18.0-6ubuntu8.2
  o nginx-common - 1.18.0-6ubuntu8.2
  o nginx-full - 1.18.0-6ubuntu8.2
  o nginx - 1.18.0-6ubuntu8.2
  o nginx-light - 1.18.0-6ubuntu8.2

Ubuntu 20.10

  o nginx-extras - 1.18.0-6ubuntu2.2
  o nginx-core - 1.18.0-6ubuntu2.2
  o nginx-common - 1.18.0-6ubuntu2.2
  o nginx-full - 1.18.0-6ubuntu2.2
  o nginx - 1.18.0-6ubuntu2.2
  o nginx-light - 1.18.0-6ubuntu2.2

Ubuntu 20.04

  o nginx-extras - 1.18.0-0ubuntu1.2
  o nginx-core - 1.18.0-0ubuntu1.2
  o nginx-common - 1.18.0-0ubuntu1.2
  o nginx-full - 1.18.0-0ubuntu1.2
  o nginx - 1.18.0-0ubuntu1.2
  o nginx-light - 1.18.0-0ubuntu1.2

Ubuntu 18.04

  o nginx-extras - 1.14.0-0ubuntu1.9
  o nginx-core - 1.14.0-0ubuntu1.9
  o nginx-common - 1.14.0-0ubuntu1.9
  o nginx-full - 1.14.0-0ubuntu1.9
  o nginx - 1.14.0-0ubuntu1.9
  o nginx-light - 1.14.0-0ubuntu1.9

In general, a standard system update will make all the necessary changes.


  o CVE-2021-23017

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